zlacker

>>todd8+(OP)
> The virus does have an inexplicable feature: a so-called “furin cleavage site” in the spike protein that helps SARS-CoV-2 pry its way into human cells. While such sites are present in some coronaviruses, they haven’t been found in any of SARS-CoV-2’s closest known relatives.

This is false. First of all it should be stated clearer that there has been parallel evolution across several branches of coronaviruses which have independently evolved a furin cleavage site (so there is evolutionary pressure and advantage for coronaviruses to follow this path):

https://www.sciencedirect.com/science/article/pii/S187350612...

And then the statement is just wrong. The related sarbecoviruses found in Thailand have similar furin cleavage sites:

> The RacCS203 S gene is most similar to that of RmYN02 (Supplementary Fig. 3a). The two viruses shared part of the furin cleavage site unique to SARS-CoV-2 (Supplementary Fig. 3b) and have an almost identical RBD aa sequence with only two residue differences out of 204 aa residues

https://www.nature.com/articles/s41467-021-21240-1

>>lamont+UZ
Yes. And making it even more obvious the extremely well known (now) story of how the researcher that discovered the technique of stablizing the spike in it's pre-fusion conformation with proline substitutions (before being acted on by furin proteases) did so while working with MERS-CoV. It's not even obscure knowledge anymore that MERS had the same furin cleavage site. It's filtered out into public non-expert awareness.